A307741 Sum of divisors of the multiply-perfect numbers.

1, 12, 56, 360, 992, 2016, 16256, 120960, 131040, 1571328, 8714160, 94279680, 67100672, 182131200, 571963392, 1379454720, 5517818880, 4428914688, 17179738112, 70912195200, 159991977600, 175445913600, 153003540480, 265734881280, 274877382656, 612014161920

Offset: 1

Author

Jaroslav Krizek, Apr 26 2019

Keywords

• nonn

Comments

When sorted, this is A081756. - N. J. A. Sloane, May 03 2019

Examples

			For n = 3; a(3) = sigma(A007691(3)) = sigma(28) = 56.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..730

Crossrefs

Cf. A000203, A007691, A054030, A088843 (tau(A007691)), A139256.

See also A081756.

Programs

Magma

[SumOfDivisors(n): n in [1..1000000] | IsIntegral(SumOfDivisors(n)/n)]

PARI

lista(nn) = {for (n=1, nn, my(s=sigma(n)); if (! (s % n), print1(s, ", ")););} \\ Michel Marcus, Apr 26 2019

Formula

a(n) = sigma(A007691(n)) = A000203(A007691(n)).

a(n) = A007691(n) * A054030(n).